Tempering furnace for small parts



March 2, 1`943.

R. GRGER TEMPERING FURNACE FOR SMALL PARTS Filed March s, 1941 2sheets-sheet 1 www,

.NQWYW/ March 2, 1943. R. GRGER 2,312,403

I TEMPERING FURNACE FOR SMALL PARTS Filed March 3. 1941 2 Sheets-Sheet 2Patented Mar. 2, 1943 UNITED STATS TEMPERING FURNACE FOR SIWALL PARTSRudolf Grger, Hanau, Germany; vested in the Alien Property Custodian 3Claims.

Thisrinvention relates to tempering furnaces, andmore particularly tosuch furnaces which are adapted especially for the tempering of smallobjects, such as balls, screws, rivets and the like.

In the past furnaces for the treatment of small objects have usuallybeen of two types, the drum type, and the push through type. The drumtype furnace presents the drawback that a careful separation of theobjects treated is necessary following termination of the heattreatment, This is necessary since, in many cases, various kinds ofsmall objects are treated simultaneously in the rotary drum. The problemis particularly difficult during the simultaneous treatment in the drumof ball bearings, the sizes of which may vary from standard by, forexample, 0.1 mm.

With the push through furnace, as the name implies, the articles areplaced in containers and as they are conveyed through the furnace theyare heat treated. The use of such furnaces gives rise, however, toimportant heat losses caused by the great space requirements, butchiefly from the .absorption of heat by the containers for the articlestreated.

A principal object of the present invention is to provide a furnace forthe treatment of small articles, which furnace obviates thedisadvantages of the furnaces of the drum type and push through type.

Another important object of the invention is the provision of such afurnace 'which makes possible the simultaneous but separate treatment ofsmall objects of various sizes and shapes and thereby an improvedutilization of the furnace capacity and simplification of operation byeliminating the necessity for subsequent sorting.

Still a further object of the invention resides in the provision of afurnace which avoids unnecessary heat losses, and for the same capacitymakes possible about a three-fold output as compared with a rotary drumfurnace.

Other objects of the invention Will be evident from the followingdescription and claims when read on the accompanying drawings in which:

Fig. l is a face view of a furnace embodying the invention;

Fig. 2 is a plan View, partially in section, of the furnace of Fig. 1;

Fig. 3 is a vertical section taken on the line 3 3 of Fig. 4; and

Fig. 4 is a Vertical section taken on the line 4 4 of Fig. 3.

As may be noted from these drawings, perhaps the characteristic dierencebetween known types of furnaces and those constructed in accordance withthe present invention resides in the fact that in accordance with thepresent inE vention similar articles to be tempered are placed inpocket-like receptacles disposed vertically within the furnace andexposed to the tempering treatment by means of air circulation. Thesereceptacles, which may take other shapes (such as a pipe-shape) arebuilt rigidly within the furnace. Each of the plurality of receptacles nthe furnace can' hold small objects and all of the objects placed in anyone receptacle should be of the same size. This avoids the necessity forsubse-A quent separation.

In the present invention the articles to be treated are heated by hotair. The air is pref erably drawn around the receptacles by a suc.- tionfan and then, by the same fan, forced past heating members located forexample at the sides of the furnace, and thence back to the recep,tacles. By using specially provided guide plates it is possible for allof the receptacles to be bathed uniformly by the hot air,

Referring now specifically to the drawings, the furnace II is mounted asuitable distance above the floor by supports I2. The furnace isgenerally rectangular in shape, with the exception however that thebottom, as shown ,in Fig. 3, has a central portion I4 which slopesdownwardly from. back to front, and side portions I6 which, as shown inFig. 4, slope downwardly and inwardly from the side walls Il of thefurnace.

Referring now to Fig. 3, the articles to be tempered, which may be ballbearings, screws, rivets, or the like, are placed in pocket-likereceptacles I8 through openings 23 in the receptacles, which openingsextend through Vthe top of the recep-f tacles and are adapted to beclosed by lids or closure members 25. 'The bottoms ofthe receptaclesslide forwardly and terminate in openings 2| to assure a completeemptying of the receptacles. As-shown in the drawings, the receptaclesmay have two similar walls in the form of parallelograms, which Wallsare spaced a relatively small distance apart. The receptacles areemptiedv through means which can be actuated from the outside of thefurnace. In the drawing figures such means are shown to be comprised ofslide closures 26, one for each receptacle. 'I'he inner end of eachslide 2S is adapted to block the corresponding opening 2I in the bottomof the receptacle I8. The outer end of each slide extends through thefront Wall I5 of the furnace and terminates in a suitable handle 28.When the handle of a slide closure 26 is grasped and drawn forwardly theslide no longer blocks its corresponding opening 2| and the smallarticles which have been disposed in that receptacle I8 fall into thebottom of the furnace and thence into a collection box disposed belowthe opening 32 at the base of the furnace. Because of the slantingportions I4 and IB of the bottom as heretofore described, the articlesfalling from the receptacles I8 travel toward the opening 32. It istherefore necessary to have only one opening 32 regardless of the numberof individual receptacles I8 disposed in the furnace.

In Fig. 2, which is a plan view of a furnace constructed in accordancewith the invention (partially in section), the arrangement of theheating element and the air circulation means are evident. The suctionfans and blower 34, supported by the back wall I3 of the furnace, forcethe air through the chamber 36. Heating elements 38 are disposed in thecham-ber 36. From there the heated air passes into the treating chamber40 in which the receptacles I8 are disposed. The hot air passes aroundthe receptacles I8 and is then drawn in again by the suction fan andblower where it is ready to start again on its continuous path ofmovement.

When the Ydimensions of the articles being treat.. ed permit it, thereceptacles I8 may be provided with perforations or slots 42 on theirend Walls,

their side walls, or both, through which the hot air can be drawn so asto pass in direct contact with the articles within the receptacle.Ordinarily the receptacles are spacedfrom each other, though thisarrangement of spaces, of course, is not of such importance when thereceptacle walls are perforated or slotted. In so far as spaces maystill remain between the receptacles, such spaces may be closed by sheetmetal mem-bers or the like so that the hot air must follow a paththrough the perforations or slots 42 in the receptacles and into contactwith the articles of the charge.

From Figs. 2 and 4 it will be seen that the heating elements 38 may beconstructed as tubular heating members which are arranged in the sidechambers 36. The elements 38, either with or without protecting sheathsor pipes, may be mounted to a cover member 44 so as to be replace; ableas a unit, or separately, Without interrupting operation of the furnace.

The furnace shown is also adapted for operation with advantage as anannealing and hardening furnace, at temperatures up to 1000 C. withoutair circulation.

Each receptacle I 8 may be provided with a time clock 46 and a controllamp 48, mounted in the front Wall of the furnace as shown in Fig. l. Bythis means each receptacle can be separately adjusted and controlled tothe required time of treat--V ment. When a charge is inserted in areceptacle, the corresponding clock therefor is set for the timerequired for the treatment, and the lamp for that clock will then lightwhen the treatment is completed. In this manner the operator will knowwhen to empty the charge from the receptacle. The simultaneous temperingtreatment of a considerable number of various kinds and sizes ofreceptacles, pipes or chutes could be secured to the receptacles toguide the treated articles from each of the receptacles directly to theplacesY where they will be subsequently worked. These and other changesmay be made without departing from the principles of the invention, andthe invention is not to be limited in scope except by the followingclaims.

I claim:

l. A tempering furnace for small objects of various sizes, comprising aheating chamber, a plurality of spaced receptacles mounted within saidchamber, including at least one receptacle for each size of the smallobjects to be treated, 4said receptacles being substantially in theshape of parallelograms of relatively narrow thickness and arrangedwithin the chamber with two sides of the parallelograms in verticalposition and the other two sides slopngdownwardly, inlet charging meansat the uppermost corner of each receptacle and extending through the topof the furnace, outlet emptyingvmeans at the lowermost corner of eachreceptacle, means extending to the outside of sai-d furnace to controlsaid outlet emptying means separately, heating elements within saidfurnace, and circulating means for directing air past said heatingelements andl into contact with said receptacles to treat the articleswithin said receptacles, each of said pocket-like receptacles havingperforations of a size smaller than the size of the articles to betreated in that particular receptacle, whereby air directed to saidreceptacles passes into actual contact with the articles treated.

2. A tempering furnace for small objectsv of various sizes, comprising aheating chamber, a plurality of spaced receptacles disposed within saidchamber including at least one receptacleV for each size of the smallobjects to be treated, each of said receptacles having separate chargingand emptying openings controlled from the outer Walls of the furnace,said emptying openings in the spaced receptacles being within thefurnace, heating means within the furnace, means for directing air incontact with said heating means and thence into contact with saidreceptacles, a closable discharge opening in the furnace spaced 'belowthe receptacles and means sloping downwardly toward RUDOLF GRGER,

